For convenience stores, particularly ones with few or no built-in wall coolers, the typical deal is the Coca-Cola or Pepsi distributor will provide and maintain a free-standing cooler, but it can only hold products from that distributor (often the distributor stocks it for you). Thus you'll typically see Coca-Cola and Pepsi products segregated in different coolers, if the store sells both.

I presume, but don't know first-hand, that for built-in coolers you want stocked by the distributor, they'll also require segregation. Frito-Lay distributors operate similarly--they'll come in and stock your shelf if you want (I dunno if there's a sales premium), but typically they'll require the Frito-Lay products be segregated, and they'll provide branded shelving if you want.